The present invention relates to clamping means for clamping a pipe or the like through peripheral clamping engagement and more particularly, to an adjustable clamping assembly of the above described type.
Up to the present, many types of clamping devices including the device for slidably clamping the pipe or the like through peripheral clamping engagement have been proposed.
The clamping device through peripheral clamping engagement mentioned above is known to be quite handy and convenient, especially for fixedly clamping the pipes or the like of the round peripheral shape, due to the fact that the clamping device of the above described type can define a plurality of clamping arrays with the adjustment of the clamping members in spaced relationship to the center axis of the object to be clamped, which may not be otherwise attained by any other types of the clamping devices.
Usually, since the device of the above described type comprises a plurality of sets or units of clamping surface members, and each set further includes a plurality of members coplanar with each other and yet, being expected to be slidable for effectively accomplishing the relative, intersliding and interleaving movement therebetween, the respective members mentioned above not only have to be provided with precise dimensions, especially precise width thereof, but also should be surface-treated to a high degree of precision.
Adjustable clamping means disclosed, for example, in Japanese Laid-Open Patent Publication No. 51-94185, Aug. 18, 1976, for clamping any one of a plurality of objects having different cross-sections includes a first sliding member having a first, substantially rectilinear slot, a second slide member having a second, substantially rectilinear slot substantially coplanar with the first slot, a third slide member having a first slide portion slidably received in the first slot, a second slide portion slidably received in the second slot, and a clamping portion between the slide portions, means for mounting the first and second members for variable spacing therebetween along a preselected line of movement with the slots extending toward each other at equal and opposite acute angles to the line of movement, the clamping portion of the third slide member being variably positioned in a direction perpendicular to the line of movement as a result of the variable spacing of the first and second slide members, the first and second slide members further defining clamping surfaces adjacent the third slide member clamping portion and defining therewith an adjustable size polygonal array of clamping surfaces facing inwardly toward a clamping space in which the object to be clamped is received for peripheral clamping engagement by the clamping surfaces, and means for forcibly effecting relative movement of the first and second slide members toward each other along the line of movement.
The prior art described above has well defined characteristics for clamping the pipes or the like through peripheral clamping engagement.
However, since the movable stack, as a whole, is clamped in order to be rigidly guided toward the longitudinal line of movement relative to the other stacks, every corresponding member to be interslid and interleaved in the other stacks should be layered, in succession, to be precisely coplanar with the corresponding member comprising the movable stack mentioned above for simultaneously accomplishing respective good peripheral engagements therebetween. Thus, as is clear from the situation mentioned above, if the effective automatically intersliding and interleaving clamping process by the arrangement described in the prior art is expected, the respective member comprising the respective clamping unit must be accordingly not only defined in quite precise dimensions, especially in respective width, but also surface-treated to a high degree of precision, to prevent the mutual interference actuation concerning the relative sliding motion therebetween.
Furthermoe, even if the conditions concerning the respective members comprising a clamping unit, which should be coplanar with each other, are satisfied, the members to be relatively interslid must be restricted in their relative movement due to the surface friction caused by the inevitable, close contact between the adjacent layers due to the reason mentioned above. Therefore, the resultant peripheral clamping must result only local and thereby, the only partial clamping units comprising the stacks are functional.
Although the undesirable situation concerning the adjustable sliding means is not specific only for the prior art indicated above, the adjustable clamping means including the intersliding and interleaving members whose relative motion is perpendicular to the line of movement of the movable stack as well as whose leg-portions to be interleaved with the slots extending toward each other at equal and opposite acute angles to the line of movement is most specifically corresponding to the situation described in the foregoing, because of the difficulties of relative actuation of the intersliding movement when compared with the other arrangements of the members provided with the other characteristics concerning dimensions and predetermined intersliding movements.